— 50 —
Grab and drag the slider knob, or highlight it and use the com-
puter’s cursor keys. The value should be set to a point just at,
or a bit above, your normal modulation peak excursion value.
Time On (Sec)
is programmed in like manner. This is the time in
seconds that an indicated peak must remain above the trigger
point to dispatch a notification or appear in the Alarm Log.
What you should be looking for is unusual modulation activity
that would indicate a processing or transmitter malfunction.
You certainly don’t want a series of text messages to your
smart phone for occasional deviation overshoots, so set
Time
On (Sec)
: accordingly. In the example it would take a continu-
ous overmodulation condition of ten full seconds to initiate an
alarm. If you got that sort of text message, something is defi-
nitely amiss.
Time Off (Sec):
is the number of seconds that carrier modulation
must remain below the Peak Flasher threshold to reset the
Peak
alarm timer. This is certainly not as critical a setting, but a
higher number here will obviate multiple notifications and log-
gings for a trouble condition that comes and goes.
Audio Loss
This alarm monitors the left- and right-channel signals inde-
pendently and has a level threshold fixed at about –10dB with
respect to 0dB on the peak-responding
DEMOD METERING
scale. This means that dead air or a missing channel will trig-
ger an alarm.
Nearly any broadcast for-
mat, even classical music
programming will con-
tain peaks that reach the
Audio Loss
trigger point.
Nonetheless, to avoid unnecessary alarms from short instances
of ‘dead air’ (or
pianissimo
passages), a
Time On (Sec):
setting
between 30 seconds and one minute is probably a safe one. If
you suspect that you have short-term dropouts and wish to be
apprised of these fleeting periods of silence you may set
Time
On (Sec):
to a small number. But pauses in speech may then in-
itiate an alarm.
As with the
Peak
alarm,
Time Off (Sec):
is not critical at all, un-
less you want to catch those very quick dropouts.
Low Signal
and
Multipath
This pair of alarms is associated more with the quality of the
off-air signal than with probable transmission problems. How-
ever,
Low Signal
is the alarm that will let you know that the
transmitter has gone off the air. As in the case of the alarms
previously described,
Time On (Sec)
can be set to a full minute
or more, as the likelihood of the transmitter shutting down and
then resetting itself in this time interval is doubtful.
There are few transmission faults that will manifest as multi-
path distortion. Reflections off aircraft and other receive-path
perturbations are more likely to cause a brief indication. Even